[patch] Update catch(...) handlers to deal with __forced_unwind

[Uros Bizjak]

Hello!

>> Failing to rethrow a __forced_unwind exception is very bad.
>>
>> This patch ensures we rethrow them in async tasks, and makes the
>> shared state ready with a broken_promise so that waiting threads
>> don't block forever. That seems reasonable to me, does anyone have any
>> better ideas?
>>
>> Tested x86_64-linux, will wait for feedback before committing.
>>
>> Committed to trunk.

    * testsuite/30_threads/async/forced_unwind.cc: New.
    * testsuite/30_threads/packaged_task/forced_unwind.cc: New.

These two tests timeout on alpha-linux-gnu:

FAIL: 30_threads/async/forced_unwind.cc execution test
WARNING: program timed out.
FAIL: 30_threads/packaged_task/forced_unwind.cc execution test
WARNING: program timed out.

strace -f of 30_threads/async/forced_unwind.cc execution test:

...
open("/lib/libpthread.so.0", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0&\220\1\0\0\0\320r\0\0\0\0\0\0"...,
832) = 832
fstat64(3, {st_mode=S_IFREG|0755, st_size=141449, ...}) = 0
mmap(NULL, 189528, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3,
0) = 0x2000027c000
mprotect(0x20000296000, 57344, PROT_NONE) = 0
mmap(0x200002a4000, 16384, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x18000) = 0x200002a4000
mmap(0x200002a8000, 9304, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x200002a8000
close(3)                                = 0
open("/lib/libc.so.6.1", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0&\220\1\0\0\0`_\2\0\0\0\0\0"...,
832) = 832
fstat64(3, {st_mode=S_IFREG|0755, st_size=1646104, ...}) = 0
mmap(NULL, 1719888, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3,
0) = 0x200002ac000
mprotect(0x20000438000, 57344, PROT_NONE) = 0
mmap(0x20000446000, 32768, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x18a000) = 0x20000446000
mmap(0x2000044e000, 7760, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x2000044e000
close(3)                                = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
0) = 0x20000450000
mprotect(0x20000446000, 16384, PROT_READ) = 0
mprotect(0x200002a4000, 8192, PROT_READ) = 0
mprotect(0x20000278000, 8192, PROT_READ) = 0
mprotect(0x20000254000, 8192, PROT_READ) = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
0) = 0x20000452000
mprotect(0x2000017a000, 24576, PROT_READ) = 0
mprotect(0x120016000, 8192, PROT_READ)  = 0
mprotect(0x20000032000, 8192, PROT_READ) = 0
munmap(0x20000024000, 41134)            = 0
set_tid_address(0x20000450e50)          = 18325
set_robust_list(0x20000450e60, 24)      = 0
futex(0x11f813260, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0x11f813260, FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME, 1,
NULL, 200002b0248) = -1 EAGAIN (Resource temporarily unavailable)
rt_sigaction(SIGRT_0, {0x20000282db0, [], SA_SIGINFO}, NULL, 8, 0) = 0
rt_sigaction(SIGRT_1, {0x20000282c70, [], SA_RESTART|SA_SIGINFO},
NULL, 8, 0) = 0
rt_sigprocmask(SIG_UNBLOCK, [RT_0 RT_1], NULL, 8) = 0
getrlimit(RLIMIT_STACK, {rlim_cur=8192*1024, rlim_max=9223372036854775807}) = 0
brk(0)                                  = 0x12001a000
brk(0x12003c000)                        = 0x12003c000
mmap(NULL, 8388608, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x20000454000
mprotect(0x20000454000, 8192, PROT_NONE) = 0
clone(Process 18326 attached
child_stack=0x20000c52ae0,
flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID,
parent_tidptr=0x20000c532c0, tls=0x20000c538e0,
child_tidptr=0x20000c532c0) = 18326
[pid 18326] set_robust_list(0x20000c532d0, 24 <unfinished ...>
[pid 18325] futex(0x20000c532c0, FUTEX_WAIT, 18326, NULL <unfinished ...>
[pid 18326] <... set_robust_list resumed> ) = 0
[pid 18326] mmap(NULL, 134217728, PROT_NONE,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x20000c54000
[pid 18326] munmap(0x20000c54000, 54181888) = 0
[pid 18326] munmap(0x20008000000, 12926976) = 0
[pid 18326] mprotect(0x20004000000, 139264, PROT_READ|PROT_WRITE) = 0
[pid 18326] futex(0x2000027a1f4, FUTEX_WAKE_PRIVATE, 2147483647) = 0
[pid 18326] futex(0x12001a08c, FUTEX_WAKE_PRIVATE, 2147483647) = 0
[pid 18326] madvise(0x20000454000, 8355840, MADV_DONTNEED) = 0
[pid 18326] exit(0)                     = ?
[pid 18326] +++ exited with 0 +++
<... futex resumed> )                   = 0
futex(0x12001a098, FUTEX_WAKE_PRIVATE, 2147483647) = 0
futex(0x12001a05c, FUTEX_WAIT_PRIVATE, 1, NULL

... the test hangs here ...

Uros.